Epidemiology, Pathogenesis, and Control of Feline Calicivirus: Current Insights and Future Directions

Abstract

Feline calicivirus (FCV) is a globally distributed pathogen and a leading cause of upper respiratory tract disease in cats, responsible for recurrent outbreaks in shelters and multi-cat environments. Its non-enveloped, positive-sense RNA genome, replicated by an error-prone RNA-dependent RNA polymerase, results in high genetic variability and the emergence of immune escape variants. FCV infection presents with diverse clinical manifestations, from mild oral–respiratory disease and limping syndrome to the severe virulent systemic form (VS-FCV). Despite extensive research, no licensed antiviral agent with proven efficacy is available; treatment remains supportive and focused on symptom relief and prevention of secondary infections. Experimental compounds such as nitazoxanide, 2′-C-methylcytidine, and recombinant feline interferon-omega show in vitro antiviral potential but require clinical validation. Vaccination remains the main preventive measure, although protection is strain-dependent and incomplete. The virus’s environmental resilience necessitates strict biosecurity measures and effective disinfection using chlorine-based or oxidizing agents. Integrated strategies combining improved vaccine design, antiviral development, and environmental control are essential to achieve sustainable management of FCV and reduce its impact on feline health and welfare.